Blew a Primer _ Analysis

[elkaholic]

Rich,
I'm going to measure the distance the BAT extractor projects inward from the rim of the bolt head recess. It may be enough to fully engage the rim of the 8x68S RWS brass. It's spring loaded. If it projects in far enough to bottom in the extractor cut behind the rim of the case, we should really have very little concern as to the reliability of fired case extraction.

You could do the same, as you've got both the RWS casing and the BAT bolt face.

In other words, if the BAT extractor projects 0.010" further than necessary to fully bottom out in the Hornady 375 Ruger extractor recess just ahead of the case rim, then the BAT extractor will also fully engage the extractor recess in the 8x68S RWS case extractor slot.

I agree. I had planned to check that also, but have not messed with the brass any more as yet.

 

[Pdvdh]

I wonder if their is a hardness issue with the copper they said on web site it was red copped. these mushroom like barnes where hammers break off. I will run the 128 .277s this weekend and compare to my known load with 126 hammer bullets. all mine measured .308 and .277 but my calipers wont do .0001 maybe if Steve is interested I can send him some .270 and .308 to check out

Please share your MV data!

Might wanna wear your shooting glasses. Just saying...

I think the MV's I'm recording in my rifles with the three different caliber/model Badlands Precision bullets are reasonable. But your direct comparison of equal weight bullets will be much more telling. A qualitative description of the relative length of baring surface would also be pertinent to the discussion.

 

[Pdvdh]

I agree. I had planned to check that also, but have not messed with the brass any more as yet.

Hoping to get you to do my homework for me! Hah...

 

[Pdvdh]

Why don't you measure total bearing surface length and compare it to that of the bullets RM is shooting. Copper bullets will be 10-12% longer than traditional cup/core bullets of the same diameter and weight so I'm wondering if even with the grooves you may have more total bearing surface than he does which could affect peak pressures with otherwise identical loads.

can1010 might be able to do that, as he has both brands of bullets. I only have the Badlands Precision bullets at this time. Pretty sure Steve's in the business to sell Hammer Bullets though... so I feel certain I could get some!

Still I have no straightforward way to collect those measurements for total baring surface. Maybe can1010 has the measuring tools required to do this. That hump back up to full bore diameter in the middle of the bullet would prevent me from using my Hornady caliper bushings to measure the length of the middle hump. I could measure the end to end length of the baring surface using two of the appropriately sized Hornady bushings. But they wouldn't measure the length of the relief cuts or the middle hump that's present between the outermost baring surfaces.

 

[WildRose]

True yesterday, true today, true tomorrow. And that's what I was thinking when Edd expressed opinion about cartridge operating pressures. I'm the one combining the witches' brew of explosive materials into a nice shiny neat container and setting them off. Doesn't make much difference the cartridge. Not like a lamb being led to slaughter. Each rifle is different. Each cartridge loaded different. I control the outcome of the witches' brew I feed into my rifle. Poof! No eyebrows due to excessive pressures - my fault.

I've only fired two bullets in my 30/375 S.I., and I still have my eyelids and eyebrows. Sacrificed one Hornady casing, perhaps a defective one at that. Not too bad...

I'd like to know why the difference - the lower pressure & MV load loses its primer. The higher pressure & MV case head survives to be reloaded another day.

Would be nice to send these two casings into ADG, Lapua, Peterson, Lake City, Federal, or another case manufacturer with the ability to test brass case head strength. But there's nothing in it for them other than ugly, so why bother. That would be the next, most logical step. But only if the option was available at a VERY low cost. Because I'm cheap.

Call Hornady and see if they would. Their customer service has always been exemplary for me and I've been annoying them occasionally for nearly three decades.

 

[WildRose]

can1010 might be able to do that, as he has both brands of bullets. I only have the Badlands Precision bullets at this time. Pretty sure Steve's in business to sell Hammer Bullets though...

Still I have no straightforward way to collect those measurements for total baring surface. Maybe can1010 has the measuring tools required to do this. That hump back up to full bore diameter in the middle of the bullet would prevent me from using my Hornady caliper bushings to measure the length of the middle hump. I could measure the end to end length of the baring surface using two of the appropriately sized Hornady bushings. But they wouldn't measure the length of the relief cuts or the middle hump that's present between the outermost baring surfaces.

If you can recover a shot bullet just measure the full length of the impressions made by the lands and subtract the total width of the cannelure grooves. That should give you pretty much the exact total length of the baring surface.

This can then be compared to the bearing surface of any slab sided bullet of similar weight/caliber.

I've got some factory Hornady 270gr SP's and could easily shoot one into a water trough and measure it if it would help. Steve could do the same with one of his and that might lead you in the right direction.

The greater the bearing surface the higher the pressures will be when comparing two bullets of similar weight.

Edit:

Ok got stuck on the .375 part of the equation and forgot about the .30 cal part.

I don't think I have any 200gr bullets in thirty caliber. The closest I'd have are the Peregrine 183's and ELDX in 220gr.

The ELD-X should be pretty close in length of bearing surface not accounting for the grooves.

 

[can1010]

I have no way to measure bearing surface accurately that is why I offered to send some to steve at hammer bullets will do my best to recover one but everything around here is pretty frozen

 

[RockyMtnMT]

Measuring baring surface with our bullet is going to take a pretty good slide rule. Because of our radiused baring surface there is no constant surface. The surface that engages the grooves is very finite and allows us to seal the bore without increading pressure. The deeper the rifling engages the bullet the more material it gets, thus giving it enough meat to hang on to. We leave enough space between bands that the displaced copper as some place to go and not continue to engage the barrel. This also cuts pressure and eliminates the fouling that is typical to mono's. In fact our bullets foul less than pretty much every bullet. At least to my knowlege.

In the end because of our patented PDR design, I don't think you can measure the baring surface. I can tell you it workes better than anything else on the market.

Yes Paul I am in the business of selling bullets, but it does not change anything I just said.

Steve

 

[Pdvdh]

If I'm not mistaken it looks like there is some scoring on the primer hole indicative of high pressure jet/heat. Do you see any on the primer itself?

What is the diameter of the primer compared to the others in the same box? An undersized primer could produce the same problem as an oversized primer pocket. Obviously not all primer pockets are going to be perfectly uniform in size, particularly those that are punched vs those that are drilled and primers are stamped rather than drilled so they too will tend to have some eccentricities.

Nope. No unusual scoring in the base of the primer pocket. That's the shadow of the primer anvil in contact with the base of the primer pocket. That's all I see in there. There is no visible torching anywhere, as is sometimes the case when high temperature and high pressure gases pierce out thru the firing pin indentation in the face of the primer, or around the perimeter of the primer. I think the gases escaped the perimeter of the primer not during the pressure rise, or even at peak pressure. I think the gas that escaped around the perimeter of the primer happened after peak pressure passed, and the brass case head relaxed to its permanently swelled to 0.215" ID, while the primer relaxed back down to it's current 0.211" OD. 0.004" of clearance for lower pressure gas to poof back against the bolt face. A smoke ring was visible on the face of the bolt. No etching/cutting as I've seen with pierced primers when full pressure gas torches out onto the bolt.

As far as the primers, I loaded the case the day before I shot it. All primers seated with normal resistance, meaning there was snug compression during seating.

 

[Pdvdh]

Yes Paul I am in the business of selling bullets, but it does not change anything I just said.

Steve

No negative thought ever entered my mind Steve.

My prior post stating your business was selling bullets was my way of saying I was pretty sure I could get some Hammer bullets for comparison. That you'd be happy to sell some.

Editing note: I went back and re-read my statement. My apologies Steve. There was no negative intention but I could have stated that better. I've revised the sentence in my Post #88 in an effort to ensure it communicates nothing more what I was thinking and meant. You've been stellar within this Thread, and I didn't intend to imply anything less.

 

[WildRose]

Nope. No unusual scoring in the base of the primer pocket. That's the shadow of the primer anvil in contact with the base of the primer pocket. That's all I see in there. There is no visible torching anywhere, as is sometimes the case when high temperature and high pressure gases pierce out thru the firing pin indentation in the face of the primer, or around the perimeter of the primer. I think the gases escaped the perimeter of the primer not during the pressure rise, or even at peak pressure. I think the gas that escaped around the perimeter of the primer happened after peak pressure passed, and the brass case head relaxed to its permanently swelled to 0.215" ID, while the primer relaxed back down to it's current 0.212" OD. 0.003" of clearance for lower pressure gas to poof back against the bolt face. A smoke ring was visible on the face of the bolt. No etching/cutting as I've seen with pierced primers when full pressure gas torches out onto the bolt.

As far as the primers, I loaded the case the day before I shot it. All primers seated with normal resistance, meaning there was snug compression during seating.

Scratch another one off the list then.

 

[RockyMtnMT]

No negative thought ever entered my mind Steve.

My prior post stating your business was selling bullets was my way of saying I was pretty sure I could get some Hammer bullets for comparison. That you'd be happy to sell some.

Editing note: I went back and re-read my statement. My apologies Steve. There was no negative intention but I could have stated that better. I've revised the sentence in my Post #88 in an effort to ensure it communicates nothing more what I was thinking and meant. You've been stellar within this Thread, and I didn't intend to imply anything less.

I didn't take any negative from your post. I actually thought it was funny. I should use the little smile heads more. I wanted to be objective in your thread without repo

 

[RockyMtnMT]

No negative thought ever entered my mind Steve.

My prior post stating your business was selling bullets was my way of saying I was pretty sure I could get some Hammer bullets for comparison. That you'd be happy to sell some.

Editing note: I went back and re-read my statement. My apologies Steve. There was no negative intention but I could have stated that better. I've revised the sentence in my Post #88 in an effort to ensure it communicates nothing more what I was thinking and meant. You've been stellar within this Thread, and I didn't intend to imply anything less.

I did not take any negative from your post. Actually thought it was funny. I should use the little smile heads more.

I wanted to be objective in your thread without representing my bullets.

Steve

 

[elkaholic]

I did not take any negative from your post. Actually thought it was funny. I should use the little smile heads more.

I wanted to be objective in your thread without representing my bullets.

Steve

Ha ha...sometimes our communication with each other mimicks that between our spouses! What we said, what we thought we said, what we meant and what we heard
It's even worse when we attempt it electronically!